A program aimed at improving cardiovascular fitness was evaluated. This program involved 298 volunteer middle-aged participants who initially had a bicycle ergometry test to calculate fitness. Other measurements included body fat (estimated by skin fold measurements) and a rating of coronary-prone personality. The participants were given their results and then offered a six-week fitness class consisting of both didactic and exercise segments. After six months, bicycle ergometry was repeated. During this period, mean calculated maximum oxygen uptake (a measure of fitness with a "normal" range of 20 mL/kg/min to 60 mL/kg/min) improved from 38.0 to 39.6 mL/kg/min (t test, P = .0001). Classifying this according to a cardiovascular fitness rating based on age and sex, with 5 being excellent fitness to 1 being very poor fitness, the mean fitness rating went from 3.08 to 3.31 (t test, P = .0001). There was no change in weight or percentage of body fat. Both those who attended the fitness classes and those who did not attend improved equally. Those who did not attend classes had higher ratings on a coronary-prone personality scale compared with those attending classes. In some groups, it appears that significant improvement in cardiovascular fitness may be initiated with a five-minute, office-based bicycle test.